Processes and Interactions Impacting the Stability and Compatibility of Vitamin K and Gold Nanoparticles

This study provides evidence on the stability of vitamin K1 (VK) in the form of phytomenadione, in the absence and presence of a therapeutic preparation, as the gold nanoparticles (AuNPs), under the effect of sodium halide ions. The degradation susceptibility of the two compounds was assessed individually and in mixtures by cyclic voltammetry and electrolysis at a constant current density assisted by UV-Vis spectrophotometry. Their interactions with the halide ions differently impact on the electrochemical processes as follows: (i) the fluoride ions weakly affects the VK/AuNP stability and compatibility; (ii) the presence of chloride ions leads to VK/AuNP stability, for a short time and restrictive compatibility; (iii) bromide ions induce instability and incompatibility of the VK/AuNP system; (iv) spontaneous interactions between VK/AuNPs and iodide ions take place, consequently defining as an unstable and incompatible system

Poly (Vinyl Butyral-Co-Vinyl Alcohol-Co-Vinyl Acetate) Coating Performance on Copper Corrosion in Saline Environment

Poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate) named further PVBA was investigated as a protective coating for copper corrosion in 0.9% NaCl solution using electrochemical measurements such as, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization associated with atomic force microscopy (AFM). The PVBA coating on the copper surface (Cu-PVBA) was modeled in methanol containing PVBA. Its inhibitory properties against corrosion was comparatively discussed with those of the copper sample treated in methanol without polymer (Cu-Me) and of untreated sample (standard copper). A protective performance of PVBA coating of 80% was computed from electrochemical measurements, for copper corrosion in NaCl solution. Moreover, AFM images designed a specific surface morphology of coated surface with PVBA, clearly highlighting a polymer film adsorbed on the copper surface, which presents certain deterioration after corrosion, but the metal surface was not significantly affected compared to those of untreated samples or treated in methanol, in the absence of PVBA

Induced Effect of Gold Nanoparticles (AuNPs) and Halide Ions on Pyridoxine Molecule Stability

The electrochemical behavior of pyridoxine was studied in 0.1 mol × L−1 NaX (X = F, Cl, Br) support electrolyte on a gold electrode using cyclic voltammetry and UV–Vis spectrophotometry. The influence of gold nanoparticles (AuNPs) on the electrochemical behavior of pyridoxine was studied. The experimental results obtained by both cyclic voltammetry and UV–Vis spectrophotometry indicate strong interactions in the B6 and NaBr/NaCl_AuNP systems, while in the NaF_B6_AuNP ternary system the results indicate a mechanism of direct electrochemical degradation of vitamin B6. The experimental results obtained for the electrochemical degradation of pyridoxine, in the presence of chloride and bromide ions, indicate strong interactions in the NaCl_B6_AuNP and NaBr_B6_AuNP systems associated with the spectrophotometric identification of the electrogenerated intermediates, while in the presence of fluoride ions no such products are identified. The development of the mechanism of electrochemical degradation of the pyridoxine molecule predicts both the formation of the corresponding electrogenerated intermediates and the steps of electro-incineration in a direct mechanism

Investigation of Polymer Coatings Formed by Polyvinyl Alcohol and Silver Nanoparticles on Copper Surface in Acid Medium by Means of Deep Convolutional Neural Networks

In order to assemble effective protective coatings against corrosion, electrochemical techniques such as linear potentiometry and cyclic voltammetry were performed on a copper surface in 0.1 mol·L−1 HCl solution containing 0.1% polyvinyl alcohol (PVA) in the absence and presence of silver nanoparticles (nAg/PVA). A recent paradigm was used to distinguish the features of the coatings, that is, a deep convolutional neural network (CNN) was implemented to automatically and hierarchically extract the discriminative characteristics from the information given by optical microscopy images. In our study, the material surface morphology, controlled by the CNN without the interference of the human factor, was successfully conducted to extract the similarities/differences between unprotected and protected surfaces in order to establish the PVA and nAg/PVA performance to retard copper corrosion. The CNN results were confirmed by the classical investigation of copper behavior in hydrochloric acid solution in the absence and presence of polyvinyl alcohol and silver nanoparticles. The electrochemical measurements showed that the corrosion current density (icorr) decreased and polarization resistance (Rp) increased, with both PVA and nAg/PVA being effective inhibitors for copper corrosion in an acid environment, forming polymer protective coatings by adsorption on the metal surface. Furthermore, scanning electron microscopy (SEM) certifies the formation of polymer coatings, revealing a specific morphology of the copper surface in the presence of PVA and nAg/PVA, very different from that of corroded copper in uninhibited solutions. Finally, the correlation of the CNN information with experimental data was reported

Interactions of Some Chemotherapeutic Agents as Epirubicin, Gemcitabine and Paclitaxel in Multicomponent Systems Based on Orange Essential Oil

In order to anticipate the effect induced by a natural product on the chemical activity of medicines simultaneously administered, spontaneous interactions of certain cancer treatment drugs such as, epirubicin (EPR), gemcitabine (GCT), and paclitaxel (PTX) with limonene (LIM)—a natural compound extracted from orange peel and known as an anticancer agent—were investigated. To estimate the stability of the drugs over time, a current density of 50 mA cm−2 was applied as an external stimulus between two platinum electrodes immersed in hydrochloric acid solution containing ethyl alcohol/water in the volume ratio of 2/3, in the absence and presence of orange essential oil (limonene concentration of 95%). The concentration variation of chemotherapeutic agents over time was evaluated by UV-Vis spectrophotometry. Kinetic studies have shown a delay in the decomposition reaction of epirubicin and gemcitabine and a paclitaxel activity stimulation. Thus, in the presence of limonene, the epirubicin half-life increased from 46.2 min to 63 min, and from 6.2 min to 8.6 min in gemcitabine case, while for paclitaxel a decrease of half-life from 35.9 min to 25.8 min was determined. Therefore, certain drug-limonene interactions took place, leading to the emergence of molecular micro-assemblies impacting decomposition reaction of chemotherapeutics. To predict drug–limonene interactions, the Autodock 4.2.6 system was employed. Thus, two hydrophobic interactions and five π-alkyl interactions were established between EPR-LIM, the GCT-LIM connection involves four π-alkyl interactions, and the PTX-LIM bridges take place through three hydrophobic interactions and the one π-alkyl. Finally, the decomposition reaction mechanism of drugs was proposed

Ceftriaxone Degradation in the Presence of Sodium Halides Investigated by Electrochemical Methods Assisted by UV-Vis Spectrophotometry

The electrochemical stability of ceftriaxone (CFTX), belonging to the third generation of cephalosporin antibiotics, was studied by electrochemical measurements recorded on a platinum electrode (Pt) in aqueous solutions containing sodium halides. The electrochemical behavior of ceftriaxone was investigated by cyclic voltammetry (CV) and constant current density electrolysis assisted by UV-Vis spectrophotometry. Cyclic voltammetry highlighted that the addition of CFTX in sodium halide solutions leads to significant changes in the hysteresis characteristics due to specific interactions with active species from electrolytes, as well as with the platinum electrode surface. After CV, when an exterior electric stimulus in short time (40 s) was applied, the UV-Vis spectra illustrated that CFTX is stable in the presence of F− ions, it is electro(degraded/transformed) in the presence of Cl− and Br− ions and interacts instantly with I− species. Electrolysis at constant current density confirms the results obtained from cyclic voltammetry, showing that (i) in the presence of fluoride ions CFTX gradually decomposes, but not completely, in about 60 min, without identifying a reaction product; (ii) chloride and bromide ions determine the almost complete CFTX electro(degradation/transformation) in 10 and 5 min, respectively, with completion of the electro-transformation reaction after 60 and 30 min, respectively; (iii) instantaneous interactions between CFTX and the iodide ions occurred

Inhibitory Properties of Neomycin Thin Film Formed on Carbon Steel in Sulfuric Acid Solution: Electrochemical and AFM Investigation

Our study aims to implement a strategy to reduce the carbon steel corrosion rate in a sulfuric acid solution, using an expired drug with adsorption affinity on the metal surface. To investigate the corrosion protection efficiency of an environmental friendly inhibitor, namely neomycin sulfate (NMS), the electrochemical measurements were applied on carbon steel immersed in 1.0 M H2SO4 solution with and without NMS. The protective layer that formed on the steel surface was studied by atomic force microscopy (AFM). The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) showed that the presence of the neomycin sulfate in acid solution leads to the decrease in corrosion current density (icorr) and the increase of polarization resistance (Rp). The mixed mechanism between physical and chemical adsorption of NMS molecules on the steel surface was proposed according to the Langmuir adsorption isotherm. AFM indicated that the NMS molecules contributed to a protective layer formation by their adsorption on the steel surface. The AFM parameters, such as root mean square roughness (Rq), average roughness (Ra), and maximum peak to valley height (Rp−v) revealed that in the presence of NMS a smoother surface of carbon steel was obtained, compared to the steel surface corroded in sulfuric acid blank solution

New Inhibitor Based on Hydrolyzed Keratin Peptides for Stainless Steel Corrosion in Physiological Serum: An Electrochemical and Thermodynamic Study

Reducing the impact of some biological fluids on bioimplants involves the control of surface characteristics by modeling the interface architecture and assembling ecofriendly thin films to retard corrosion. Therefore, a mixture of hydrolyzed keratin peptides (HKER) was investigated as a corrosion inhibitor for 304L stainless steel (SS) in physiological serum (PS), using electrochemical measurements associated with optical microscopy and atomic force microscopy (AFM). The tests, performed for various concentrations of the inhibitor at different temperatures, showed that the inhibition efficiency (IE) decreased with a rise in temperature and proportionally increased with the HKER concentration, reaching its maximum level, around 88%, at 25 °C, with a concentration of 40 g L−1 HKER in physiological serum. The experimental data best fitted the El-Awady adsorption model. The activation parameters (Ea, ∆Ha and ∆Sa) and the adsorption ones (∆Gads0, ∆Hads, ∆Sads) have highlighted a mixed action mechanism of HKER, revealing that physisorption prevails over chemisorption. AFM parameters, such as the average roughness (Ra), root-mean-square roughness (Rq) and maximum peak-to-valley height (Rp−v), confirmed HKER adsorption, indicating that a smoother surface of the 304L stainless steel was obtained when immersed in a PS-containing inhibitor, compared to the surface designed in blank solution, due to the development of a protective layer on the alloy surface